so to begin to quote incomitatus and answer this little block of questions he puts to us:
1. What are the strengths of my faction? What are my weaknesses?
as a evil player, your strengths are numbers and cheap units with some seriously damaging units in between
2. What are the strengths of my most likely enemies? What are their weaknesses?
your enemys are going to be smaller in number, more expensive, yet far stronger
3. What does the surrounding territory offer that I can take quickly?
mostly strategic value and denying the coins to your enemy to build those nasty elites
4. What do I have to do/seize to be sure I can be secure from my enemies?
constant expansion, knowing my weaknesses
5. Do I benefit more by expansion or development at this time?
expansion most of the game, explained later
6. Can my current situation allow me to grow stronger faster than my enemies?
no, your mostly going to have alot of your 'normal' infrantry from the start, yet with a good fight you will prevail for the dark lord.
7. Do I have potentially useful allies, and if so, do I need to help them? Can I?
yes you do, and generally they dont need help!
so to begin
your armies
Orcs - Orcs are cheap, ugly and useful cannon fodder. the idea with orcs is that you surround and envelope your enemy in numbers to make them rout or hit them in areas weak to them, such as the rear. generally speaking i find raiders do good for the flanking, and the spears for the frontal attack, they kill little but absorb damage better.
Snaga - snaga are worse then orcs, yet happily they are far cheaper. their javelins are totally devastating, the normal infrantry snaga are usefull for charging enemy archers (who cares if they die, just stop the enemy from firing!) easily replaced as well. can also be used for enveloping and flanking enemy units in conjunction with the orcs if you dont have enough orcs or have lost a lot. a nice tactic if your army is heavy on snagas is to send in the snagas on the enemy 1st to tire them out and then use orcs to fight effectively reducing casualtys on your orcs and making them last longer. and once again, Snaga Skirmishers ARE BRILLIANT! send them against dwarves on skirmish mode en masse, they do huge damage, fire them on those amazing gondor cavalry while they are engaged with other snaga/orcs, and they turn to paper mashe!
Orc/snaga archers - are effectively worthless other then to soak up enemy shots, your simply better off charging in their with your orcs instead of a shootout. can be usefull in sieges and flanking.
Heavy Halberds - OOTM and gundabad heavy halberds are really good troops despite their very slow walking speed. you need too shield these with the orcs, get the orcs in combat and order the halberds to walk through the enemy lines (click just behind the enemy unit) once most of them are in the middle of the enemy units click attack and watch them carve them up! especially useful against enemy armoured units (gondor, elves) and in sieges their slowness isnt a problem really even on attack as long as you get em past the archers ok.
morannon guard - only available to mordor these are a bit better then the goblin halberds, they move like normal units. these are your elite guys, they should be doing the flanking, killing enemy bodyguards, and being protected the most. use in a similar fashion to the above.
Trolls - This is your trump card the, huge HP heavy hitting and knock down units, extremely effective and capable of winning entire battles that are going lopsided for you on thier own. locked morale so they cant rout too! however, that doesnt mean they should go charging headlong into the foght (much like you see the stupid ai do). dont orde rthem to attack the same time as other orcs either they run very fast and will reach the enemy early. the trick with trolls is to engage AFTER the orcs have, and preferably from the sides or rear. they can also be very deadly bodyguard killers since they can rech the cavalry before they build momentum to run away, though dont use them on eleven foot bodyguards unsupported as they are nasty sods. you need to watch out for archers, archers en masses (4 units or more) concentrating fire on the trolls is a death blow, you might not see it but those arrows are actually reducing the hit points of your trolls making them very weak and able to be killed very easily in melee. also siege weapons(catapult balista) goes without saying. in sieges trolls can oddly enough be sent up ladders onto walls and practically wipe out anything up there thanks to the close confines, use this to your advantage, this is the only time id recommend throwing the trolls in 1st. Olog-Hai for morder are the same as above but more armoured better attack and more resilient, essentially are more buffed version. make sure you charge with the trolls, its very devastatng
Goblin/orc/uruk Bodyguard - these guys are all actually ok in a fight however the general always seems to die extremely fast! try to keep them away from the main fight or flank, you wont be relying on these a lot like you do with the good faction bodyguards due to the apparent frailty of the general. last resort option.
Nazgul - Epic. simple word and damned true. these are some of the best cavalry in the game capable on the charge of killing gondor generals and still holding up well in a standing melee. their special ability, strikes terror in the hearts of the enemy and may cause a general rout of the entire enemy army. a nice tactic is to use all the nazgul you get in one army and pop this morale shock on each one just after each other since it seems to stack (needs confirmation, but in my battles seems to work)at the same time order all of them to charge at same time. you will almost certainly rout the entire army unless the general is high in chivalry. downside is any other stack you field will be down one epic general to lead it!
general field tactics
on the field
Ok, so you have masses of orcs now what to do with them? throw them at the shiny plate wearers of course! best tactic to start a battle with orcs is to line all your orcs in one very long stretched line hopefully totally outstretching the enemy line, the idea is that when you close for combat your line goes around the sides of the enemy armys allowing for that flanking manouver i keep blabbing on about. use your orc spears to soak up any cavalry charge (dont worry about losses to the spears - easily replacable) and then try attack with a halberd units, if you lack them then send in more speard to overwhelm. you will want to get rid of the enemy archer quickly, try and do so with nazgul, or skirmishers of your own in loose formation to soak up the fire until you manage to get a melee unit around there. if you have trolls you should have moved them on the flanks to help wipe out cavalry and archers, and then moved into the rear of enemy melee units where they do their best damage.
In a siege
your best best is to hold on the walls themselves or in the centre, you will want a timer victory here since it takes the enemy a long time to smash through your units which are high in number, try not to commit all your units at once, only sending in more orcs once your other units has been all but detroyed. this keeps them fresh and ready to last a bit longer in the fight. commit your best units right at the end when the enemy is totally tired, for maximum damage. deploy trolls on walls if you can, they will last a long time up there. otherwise standard tactics you all know and love, archer fire on units blocked in the gates, or the catapult stew if your so inclined.
To conclude
your units are high in number cheap yet weak, they are expendable, dont get attached to your lowly orc as you would with that gondor milita that has survived 5 sieges at osgiliath, or the elven swordman who have somehow maaged to kill half a enemy army with just 10 men and live to tell the tale, your orcs are there to die and little else, firing on your orcs with your own archers and skirmishers if the enemy is fielding something tough like fountain guard or elven bodyguard is fine and even encouraged. you need to expand quicker then your enemys, you really dont want to see the elves best archer units or gondors finest on the field until you can afford and are fielding multiple stacks with trolls.
good luck servants of morgoth, your going to need it!